Quick question

[selavia]

Okay, here's the situation. haven't been punching the gas for awhile...driving like a granny cuz I'm trying to get +500 miles to a tank of gas. My fuel economy is okay; not as good as it used to be; when I first go the car I would get well over 500 with normal, not even careful use; now it's just getting to 500. But the other day I gunned it all the way 5k rpms and afterward there was a distinct smell of rotting eggs...and I'm thinking O2 Sensor; but no other symptoms; gas mileage is relatively okay...still averaging about 30mpg for really careful driving; no rough idle at all, ever, during warm up when freezing, etc; no CEL. Every once in awhile I'll smell the rotting egg smell, usually after I take it to 3k rpms. (I tend to say under 2.5k)

Does this suggest O2 Sensor? Could it be something else? Cat? (<-- only other thing I could think of)

it's the 1.8L engine, not 1.9L. 132,000 miles; o2 sensor is still original; would it be a good idea to replace it anyway b/c of the high mileage?

Any feedback is appreciated. Thanks.

Sean

 

[Big Daddy]

Usually when you get the rotten egg smell it is a cat that is faulty. Doesn't mean that the o2 sensor isn't bad as well, are you getting any warning lights on the dash? It may well be that since you are driving very cautiously, when you accelerate hard you are simply "flushing" the system and nothing is wrong. I occassionally accelerate hard to flsuh my system of carbon, mainly after periods of easy driving or after the car has been sitting for a period of time.

 

[grasutu]

Wow !!! Sean 500 miles ?????Damn i get just 350 -360 on the good days ussualy is 300 miles per tank!!!And i think is the same engine ! Congrats man !!! How r u doing it ?

 

[selavia]

Wow !!! Sean 500 miles ?????Damn i get just 350 -360 on the good days ussualy is 300 miles per tank!!!And i think is the same engine ! Congrats man !!! How r u doing it ?

1. By watching the mpg needle more than the road.
2. Noticing which roads are down hill and taking those roads instead of uphill roads [I'm not even kidding]
2. Specifically planning my day around times went traffic is lightest.
3. Taking highways whenever possible
4. Regularly (once a month use fuel injector cleaner)
5. Checking tire pressure whenever I fill gas.
6. If I'm approaching a red light, I'll reduce speed ahead of time so I don't have to come to a complete stop, which will consume more gas

I know all of these seem like only miniscule gains, but trust me it adds up. Dude, I think I could get it to 600 if I replaced the exhaust, put a CAI, and replaced o2 sensor.
If I wasn't on such a tight budget, I probably wouldn't take such extreme measures, but I'm not working right now and I feel like a bum asking my parents for gas money, ya know?

300 seems low. Do you drive her really hard?

 

[selavia]

Usually when you get the rotten egg smell it is a cat that is faulty. Doesn't mean that the o2 sensor isn't bad as well, are you getting any warning lights on the dash? It may well be that since you are driving very cautiously, when you accelerate hard you are simply "flushing" the system and nothing is wrong. I occassionally accelerate hard to flsuh my system of carbon, mainly after periods of easy driving or after the car has been sitting for a period of time.

No light shows on the dash; I was thinking cat, cause I think mine is on it's way out...making some rattling every now and then, but to be honest, I don't want to replace it. Too much $$ right now. Plus, if I replace it, I'm gonna want to replace the exhaust as well, cause I think the baffles are going.

I was thinking that about the driving cautiously bit, but the odor is overpowering; it's not slight. It takes a good 3-5 minutes for the odor to disipitate. I've heard that when it's just 'flushing' that it's a faint smell, not terribly strong. Any thoughts on this, Dan?

 

[Big Daddy]

You are most likely correct and the cat needs replacing. I have heard that in some cases they can be "serviced", however I am not a cat expert.

 

[DSK]

O2 sensors get blamed for quite a few faults when there is usually nothing wrong with them. I recently changed the CAT and 02 sensors (x2) on my 328i. OE NGK/NTK Sensors were £52 each and the CAT was £234. Not too bad!! (These were from independant BMW parts specialists and the CAT was from a CAT manufacurer direct).

If your CAT is rattling, I'd say the monolinth inside has started to disintegrate (rather than it getting blocked) which is one of the few ways a CAT is likely to fail. It is standard practice to replace the O2 sensor when a new CAT is fitted though! Also, are you certain that your Air Flow/Mass Meter is functioning correctly as this can cause air/fuel ratio problems.

 

[slickbrave]

Since we're talking about mpg, I'll make my pitch for replacing the air in your tires with nitrogen. I've noticed 2-3 mpg more and you never have to check your pressure. Well worth the money.

 

[grc]

"I think I could get it to 600 if I replaced the exhaust, put a CAI, and replaced o2 sensor"

actually hot air will get better mileage. cooler air requires a richer mixture, that's why carb'd cars need the choke working when it gets cold out. EFI cars just do it electronically.

ever hear of smokey yunick? http://www.schou.dk/hvce/?mode=2

 

[selavia]

"I think I could get it to 600 if I replaced the exhaust, put a CAI, and replaced o2 sensor"

actually hot air will get better mileage. cooler air requires a richer mixture, that's why carb'd cars need the choke working when it gets cold out. EFI cars just do it electronically.

ever hear of smokey yunick? http://www.schou.dk/hvce/?mode=2

I did not know that. I was basing my comment on one experience I had; a 2.2L 4 cyl. Toyota 5sfe motor. Put a cold air intake and gas mileage went up noticeably. I made an assumption based on that.

GRC, can you explain a little more why that is the case, I am interested in learning the correct thing.

Thanks, Sean

 

[selavia]

Also, are you certain that your Air Flow/Mass Meter is functioning correctly as this can cause air/fuel ratio problems.

Fairly certain, but then again i don't know how to check; is there a way to check?

 

[grasutu]

Not really hard ....i don't go at the red line often but ....maybe my foot is a little 2 heavy but ...and mine is a manual probably that makes a small diference . But i was sure happy when i got 360 .And probably the fact that i drive a lot in town and not on highways....
I 'll try to follow some of your " steps" see if i can improve it !

 

[selavia]

Not really hard ....i don't go at the red line often but ....maybe my foot is a little 2 heavy but ...and mine is a manual probably that makes a small diference . But i was sure happy when i got 360 .And probably the fact that i drive a lot in town and not on highways....
I 'll try to follow some of your " steps" see if i can improve it !

I got a manual too. One thing that I noticed I used to, I give it way too much gas when I'm first in line at a light, I for some insane reason think it's a 'race' and I had quite heavy foot; that was (i think) a big gas saver for me...stop doing that. lol.

I'll just be happy when I can fill up the tank for under $30.

 

[grasutu]

Yep .... i do that every time ....i guess it s just the male ego ... lol !

 

[frolf]

i have a solution and i don't mean to sound like an ass but.....



if you got a job.....
you could......

have a heavier foot and not allow the sludge to continue to build up in your motor from soft footing your car

AND


you wouldn't have to think twice about being first in line at a stop light, every green is a go.


just a thought. cheers